1. Field of the Invention
The present invention generally relates to a portable instrument for electro-optically reading indicia, such as a bar code symbol, a signature, or an object image of any object, and for selectively projecting a bit-mapped display image on a viewing surface.
2. Description of the Related Art
Various optical scanning systems and readers have been developed heretofore for reading indicia such as bar code symbols appearing on a label or on the surface of an article. The bar code symbol itself is a pattern of graphic indicia comprised of a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers function by electro-optically transforming the spatial pattern represented by the graphic indicia into a time-varying electrical signal, which is, in turn, decoded into data which represent the information or characters encoded in the indicia that are intended to be descriptive of the article or some characteristic thereof. Such data is typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control, distribution, transportation and logistics, and the like.
A variety of scanning devices is known. The scanner could be a wand type reader, such as shown in U.S. Pat. No. 5,508,504, herein incorporated by reference, including an emitter and a detector fixedly mounted in the wand, in which case the user manually moves the wand across the symbol. As the wand passes over the bar code symbol, the emitter and associated optics produce a light spot which impacts on the symbol, and the detector senses the light reflected back from the light spot passing over each symbol. Alternatively, an optical moving spot scanner scans a light beam, such as a laser beam, across the symbol; and a detector senses reflected light from the beam spot scanned across the symbol. In each case, the detector produces an analog scan signal representing the encoded information.
Moving spot scanners of this general type have been disclosed for example, in U.S. Pat. No. 4,387,297; No. 4,409,470; No. 4,760,248; No. 4,896,026; No. 5,015,833; No. 5,262,627; No. 5,504,316 and No. 5,625,483, all of which have been assigned to the same assignee as the instant application and each of which is hereby incorporated by reference. As disclosed in some of the above patents, one embodiment of such a scanning system resides, inter alia, in a hand held, portable laser scanning device supported by a user, which is configured to allow the user to aim the scanning head of the device, and more particularly, a light beam, at a targeted symbol to be read.
The light source in a laser scanner bar code reader is typically a semiconductor laser. The use of semiconductor devices as the light source is especially desirable because of their small size, low cost and low voltage requirements. The laser beam is optically modified, typically by an optical assembly, to form a beam spot of a certain size at the target distance. It is often preferred that the cross section of the beam spot measured in the scanning direction at the target distance be approximately the same as the minimum width in the scanning direction between regions of different light reflectivity, i.e., the bars and spaces of the symbol. Although typical readers utilize a single laser source, other bar code readers have been proposed with two or more light sources of different characteristics, e.g., different frequencies.
In the laser beam scanning systems known in the art, a single laser light beam is directed by a lens or other optical components along the light path toward that includes a bar code symbol on the surface. The moving-beam scanner operates by repetitively scanning the light beam in a line or series of lines across the symbol by means of motion of a scanning component, such as the light source itself or a mirror disposed in the path of the light beam. The scanning component may either sweep the beam spot across the symbol and trace a scan line across the pattern of the symbol, or scan a field of view of a photodetector, or do both. The laser beam may be moved by optical or opto-mechanical means to produce a scanning light beam. Such action may be performed by either deflecting the beam (such as by a moving optical element, such as a mirror) or moving the light source itself. U.S. Pat. No. 5,486,944 describes a scanning module in which a mirror is mounted on a flex element for reciprocal oscillation by electromagnetic actuation. U.S. Pat. No. 5,144,120 to Krichever, et al., describes laser, optical and sensor components mounted on a drive for repetitive reciprocating motion either about an axis or in a plane to effect scanning of the laser beam.
Because of the size and optical and electronic complexity of scanning systems and bar code readers, they generally have heretofore not been combined with other devices in the same housing. The conventional use of a liquid crystal display (LCD) on such readers occupies a large viewing area and limits any proposed reduction in size for a handheld system.
Also known is a laser pointer which is a device that projects a spot of light on a target, such as a presentation being made by a lecturer to an audience. The pointer is essentially a flashlight-type device and is usually packaged in a tubular housing.